The present invention relates generally to panel interlocking arrangements by which a pair of panels can be secured together in an overlapping relationship, and more particularly to an interlocking arrangement for panels wherein a winged locking tab forms a cooperative locking engagement with a retaining tab while being engaged at its base by a portion of the perimeter of a locking aperture and at its wing by another portion of the perimeter. The present invention also relates to a carton employing the interlocking arrangement and a carton blank from which the carton is formed.
In the packaging of articles, and particularly of one or more articles in wrap-around type paperboard cartons, interlocking arrangements are frequently used for maintaining closure of the carton about the articles. It can be appreciated that such interlocking arrangements must be securely and reliably engaged, and must remain in such condition until the carton is opened.
One well-known form of interlocking arrangement comprises a locking tab and a cooperating retaining tab. An example of this type of locking arrangement can be seen in U.S. Pat. No. 4,077,095 which is hereby incorporated by reference. In this patent, first and second opposite end panels of a blank are secured together in an overlapping relationship by locking and retaining tabs. The locking tab is struck from and foldably joined to the first panel whereas the retaining tab is struck from and foldably joined to the second panel. A locking aperture is defined by the retaining tab in the second panel. The blank is applied to a group of articles, and then the first and second panels are brought into an overlapping relationship whereupon the locking tab is folded into the locking aperture. Upon insertion of the locking tab, the retaining tab is thrust aside and is thereby also folded to bring its distal end into abutment against the lower side of the locking tab. By this means, the locking tab is retained in the folded position in the locking aperture with the perimeter of the aperture in engagement with the locking tab.
Wraparound cartons are tightly wound around groups of articles with no slack to assure that the articles are held inside the cartons. Therefore, the interlocking arrangement such as mentioned above continually undergoes tension. If a carton with such an interlocking arrangement is subjected to vibration during, for example, its transportation, the locking tab could be unfolded to some degree, which in the worst case could result in disengagement of the retaining tab from the underside of the locking tab. Once the tabs are disengaged, the carton could be loosened to the extent that the accommodated articles are dislodged from the carton.
What is needed, therefore, is an improved panel interlocking arrangement wherein unfolding of the locking tabs are resisted to ensure against disengagement of the tabs.